The overall objective of the Transgenic and Homologous Recombination Core is to provide program project investigators with the ability to utilize animal models in the execution of their proposed research projects as well as establish new animal models in the execution of their proposed research projects as well as establish new animal models for the investigation of the mechanisms involved in the regulation of cardiac development. Although the use of mouse models provide an invaluable source of reagents for investigating regulatory mechanisms Transgenic and Homologous Recombination Core will serve as a resource for the execution and training the use of all animal manipulations needed in this Program Project proposal. The Transgenic and Homologous Recombination Core will minimize the cost of utilizing animal models in this Program Project by consolidating the equipment, expertise and animal resources. This will ensure an efficient use of Animal research at minimal cost.